The present invention relates to a flat cable, wherein a flexible insulation sheath is used for enclosing one or a plurality of metal conductors, which is substantially flat and includes bends that make the conductor longer than the insulation sheath enclosing it so as to enable a substantial change in the conductor length upon extending or contracting the insulation sheath without breaking the conductor.
The invention relates also to a method for the manufacture of such a flat cable by extruding a plastic insulation sheath around flat conductors.
This type of flat cable is prior known from the publication print DE-1,415,692. It has the advantage that the risk of breaking the conductors is virtually eliminated while the cable can be bent to sharp angles and extended even as a result of rough handling. However, this prior known electric cable suffers from the defect that the joints cannot be made reliably by means of pins pierced through the insulation sheath without stripping the electric cable. Another drawback is that the cable is difficult to bend to permanent flexural shapes (bends) in the plane of the flat.
The electric harnesses for automobiles and vehicles in general are traditionally designed by extending separate wires to service points, such as signal lamps and headlights, by way of operating switches and fuses. All signal and warning lights have also been implemented by means of separate wires. A result of this is that the automobile electric harnesses constitute a labour-intensive and remarkably expensive part of an automobile. A second problem is the defect sensitivity of such electric harnesses, which is caused by a large number of joints between conductors and various components as well as by the fact that the conductors have a remarkably long total length, resulting in a considerable possibility of short circuits, e.g. as a consequence of attrition. The localization of contact faults and short circuits and the mending of defects in such electric harnesses is troublesome.
International patent application WO 93/10591 discloses an improved system, wherein the signal lamps and other such electrically operated items are connected in parallel to a common or just a few wire, whose conductor is supplied with a code in view of controlling the operation of the lamps and other such actuators. The lamp base or socket is provided with necessary electronics for identifying an operation control code intended for a particular lamp or some other actuator. This arrangement can be used for essentially simplifying the electric harness of an automobile for a substantial reduction in total costs and susceptibility to defects.
An object of this invention is to improve a flat cable of the above-mentioned type to make it useful especially in a system as set forth in the cited Patent publication WO 93/10591 or in a similar system. A first condition of this is that joints between a flat cable and actuators to be connected therewith can be made reliably through the insulation sheath without stripping the electric wires and a second condition is that the cable can be provided with permanent bends in accordance with the design of a vehicle.